--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/buildSrc/src/main/kotlin/RepositoryChangeset.kt	Fri May 08 21:33:19 2020 -0400
@@ -0,0 +1,52 @@
+package com.geekorum.build
+
+import org.gradle.api.Project
+import java.io.File
+import java.io.IOException
+import java.util.concurrent.TimeUnit
+
+internal fun Project.getGitSha1(): String? = runCommand("git rev-parse HEAD", workingDir = projectDir)?.trim()
+
+internal fun Project.getHgSha1(): String? = runCommand("hg id --debug -i -r .", workingDir = projectDir)?.trim()
+
+internal fun Project.getHgLocalRevisionNumber(): String? = runCommand("hg id -n -r .", workingDir = projectDir)?.trim()
+
+fun Project.getChangeSet(): String {
+    val git = rootProject.file(".git")
+    val hg = rootProject.file(".hg")
+    return when {
+        git.exists() -> "git:${getGitSha1()}"
+        hg.exists() -> "hg:${getHgSha1()}"
+        else -> "unknown"
+    }
+}
+
+/**
+ * Compute a version code following this format : MmmPBBB
+ * M is major, mm is minor, P is patch
+ * BBB is build version number from hg
+ */
+fun Project.computeChangesetVersionCode(major: Int = 0, minor: Int = 0, patch: Int = 0): Int {
+    val base = (major * 1000000) + (minor * 10000) + (patch * 1000)
+    return base + (getHgLocalRevisionNumber()?.trim()?.toIntOrNull() ?: 0)
+}
+
+private fun Project.runCommand(
+    command: String,
+    workingDir: File = File("."),
+    timeoutAmount: Long = 60,
+    timeoutUnit: TimeUnit = TimeUnit.MINUTES
+): String? {
+    return try {
+        ProcessBuilder(*command.split("\\s".toRegex()).toTypedArray())
+            .directory(workingDir)
+            .redirectOutput(ProcessBuilder.Redirect.PIPE)
+            .redirectError(ProcessBuilder.Redirect.PIPE)
+            .start().apply {
+                waitFor(timeoutAmount, timeoutUnit)
+            }.inputStream.bufferedReader().readText()
+    } catch (e: IOException) {
+        logger.info("Unable to run command", e)
+        null
+    }
+}